Validity of BMI, hip and waist circumferences as surrogate measures of obesity in a cohort of Sri Lankan premenopausal women

Abstract

BMI, hip and waist circumferences (HC and WC) are being used as clinical surrogates of obesity. Unceratinities exist regarding the cut-off values, which are recommonded for Western countries. We conducted a study to determine cut-off values for Sri Lankan women. Healthy premenopausal women (n=128) aged 25 to 50 years were selected randomly, from local MOH area and stratified into four groups (32 in each) according to their BMI. Those who were pregnant, breast feeding, or on long-term medications were excluded. Body weight and height, hip circumference (HC) and waist circumference (WC) were measured, using standard protocols. Lean and fat mass, were measured by DXA and percentage FM (%FM) was calculated (FM/body weight x100). Women with %FM> 30% were considered obese. BMI moderately correlated (r = 0.41) with %FM and BMI accounted for only 16% (r2 = 0.16) of %FM variation. Regression equations were used to estimate the cut-off values that corresponded to %FM of 30. Those cut-off values for BMI, WC, and HC were 24.4 Kg/m2, 92 cm, and 78 cm, respectively. BMI, WC and HC values of 24 kg/m2, 92 cm and 78 cm can be considered appropriate cut-off values when detecting central obesity in premenopausal women.